LHC Lifetime Frontier and Visible Decay Searches in Composite Asymmetric Dark Matter Models

TL;DR

This paper explores how upcoming experiments like LHC lifetime frontier and fixed-target setups can detect long-lived dark hadrons in composite asymmetric dark matter models, especially via dark photon portals.

Contribution

It analyzes the potential of various experiments to discover dark hadrons in composite asymmetric dark matter models through visible decay searches, highlighting the complementarity of collider and fixed-target experiments.

Findings

LHC lifetime frontier can detect dark nucleons with kinetic mixing $ \, extgreater \, 10^{-4}$.

Fixed-target experiments like SeaQuest are sensitive to sub-GeV dark pions with similar mixing angles.

Projected sensitivities are comparable to future dark photon search experiments such as Belle-II and LHCb.

Abstract

The LHC lifetime frontier will probe dark sector in near future, and the visible decay searches at fixed-target experiments have been exploring dark sector. Composite asymmetric dark matter with dark photon portal is a promising framework explaining the coincidence problem between dark matter and visible matter. Dark strong dynamics provides rich structure in the dark sector: the lightest dark nucleon is the dark matter, while strong annihilation into dark pions depletes the symmetric components of the dark matter. Dark photons alleviate cosmological problems. Meanwhile, dark photons make dark hadrons long-lived in terrestrial experiments. Moreover, the dark hadrons are produced through the very same dark photon. In this study, we discuss the visible decay searches for composite asymmetric dark matter models. For a few GeV dark nucleons, the LHC lifetime frontier, MATHUSLA and FASER, has a potential to discover their decay when kinetic mixing angle of dark photon is $\epsilon \gtrsim 10^{-4}$. On the other hand, fixed-target experiments, in particular SeaQuest, will have a great sensitivity to dark pions with a mass below GeV and with kinetic mixing $\epsilon \gtrsim 10^{-4}$ in addition to the LHC lifetime frontier. These projected sensitivities to dark hadrons in dark photon parameter space are comparable with the future sensitivities of dark photon searches, such as Belle-II and LHCb.